Milane Frantz

Net worth: $5.5 billionSource: pipelinesAge: 44Forbes 400 rank: 77Milane Frantz is one of four siblings who are heirs to their late father Dan Duncan's energy pipeline empire. He founded Enterprise Products Partners, which owns 51,000 miles of natural gas, oil, and petrochemical pipelines. Thanks to a rise in Enterprise Products' share price on the New York Stock Exchange and a generous dividend plan, Milane and her siblings find themselves each richer than a year ago. Their father died in 2010 at age 77.